1. Field of the Invention
The present invention relates to gaskets generally and, more particularly, to a novel compound gasket which is especially useful in high temperature and high pressure service.
2. Background Art
Gaskets are well known devices for sealing between mating surfaces of opposing members such as flanges and typically are formed of a resilient or semi-resilient material, frequently of metal, asbestos, rubber, or a synthetic. The gasket material deforms slightly as the two mating surfaces are drawn together, in order to conform to imperfections in the surfaces, to compensate for non-parallel alignment of the surfaces, and, thereby, to seal the joint between the surfaces.
One problem with conventional gaskets for high temperature service is simply finding appropriate materials for the temperatures and pressures encountered. High temperatures and pressures under consideration here are pressures of about 900 psi and temperatures of about 1000 degrees Fahrenheit, or greater. A further, and related, problem with gaskets is that of controlling the degree of deformation of the gasket as the mating surfaces between which the gasket is placed are drawn together. Too little deformation can result in leakage past the gasket. Too much deformation can result in destroying the resiliency of the gasket so that cyclical temperature changes can produce leaks, as the gasket cannot expand to accommodate slight changes in distance between the mating surfaces resulting from thermal expansion and contraction or resulting from mechanical stresses.
One type of compound gasket employs a center core of asbestos with annular rings of copper or stainless steel on each surface of the gasket and having ridges around the opening in the gasket. This type of gasket is relatively satisfactory for high pressure service, since the annuli prevent the asbestos from being blown out from between the mating surfaces. However, since the asbestos takes most of the compression and it is permanently deformed, the gasket not particularly satisfactory for high temperature service and cannot be reused. Also, copper is not satisfactory for use at high temperatures.
Accordingly, it is a principal object of the present invention to provide a gasket suitable for pressures of about 900 psi and temperatures of 1000 degrees Fahrenheit, or greater.
It is a further object of the invention to provide such a gasket which is reusable.
It is another object of the invention to provide a gasket with which the degree of deformation thereof is inherently controlled.
It is an additional object of the invention to provide such gaskets which are easily and economically manufactured.
Other objects of the present invention, as well as particular features and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.